Many types of apparatus have been designed to allow a swimmer to breathe underwater.
The simplest, a snorkel, is simply a tube which extends from the swimmer's mouth to the surface. The disadvantage of the snorkel is that a swimmer would have to hold his breath to go any deeper than the surface of the water.
Another method for a diver to breathe underwater is to have a pump located on the water's surface on a boat or separate float. Air is then supplied through a hose and regulator or may simply be fed into a pressurized suit worn by such diver, as has been used for many years for deep sea diving.
Another apparatus is a pressurized tank of air, which a diver wears on his back to supply air through a hose and regulator in the diver's mouth. This is the "Self Contained Underwater Breathing Apparatus" or SCUBA, which was popularized by Jacques Cousteau in the early 1950's. The diver can breathe at depths below the surface with tank pressure sufficient to compensate for water pressure at a particular depth. However, there is a need for extensive training for such a device.
Another apparatus has been designed to float independently on the surface of the water and pump air to a submerged swimmer. Typically such a device consists of an air compressor and a gasoline engine attached to a float tube. However, the gasoline engine is heavy and requires combustible fuel, and there are risks of contamination of the diver's air supply from the exhaust of the gasoline engine.
Electrically powered compressors are cleaner but they produce an electrical arc at the armature of their motor. This arc is potentially dangerous, and gases (including hydrogen) emitted by the battery can cause safety problems.
Traditionally, diving devices use electric motors and compressors that are open to the environment and are cooled by ambient air, which causes excessive heat buildup, reduces battery life, and requires continual maintenance due to environmental exposure. There is a need for a small, floating, electrically powered diving device that uses a sealed motor and compressors that are water cooled to increase efficiency, protect electrical components, and supply breathing air to a diver.
The following U.S. patents are representative of the prior art:
Taylor's "Catamaran for Underwater Exploration", U.S. Pat. No. 3,400,680, is a floating air compressor and propulsion unit. Typical of the prior art, the compressor is located above the floatation unit, hence above the water level.
Evans' "Floating Pump", U.S. Pat. No. 3,470,822, uses a gasoline-powered engine on a float, driving a semi-submerged pump. Unlike the present invention, however, the pump is a centrifugal water pump with an inlet below the water level, used for pumping water for fire fighting purposes. The dangers and disadvantages of using a gasoline engine are discussed above, although the concern of air-supply contamination is not relevant in Evans' water-pumping.
Mitchell's "Underwater Breathing Apparatus", U.S. Pat. No. 4,674,493, is a floating compressor for providing air to a swimmer. The motor and pump are contained in a sealed floating container, which prevents contact between the compressor and the water.
The present inventor's 1994 US patent, "Underwater Breathing Apparatus", U.S. Pat. No. 5,327,849, is a floating electrical compressor, in which a floatation device supports a combination of two containers above the surface of the water. The top container, in the form of an inverted box, holds one or more electrically powered compressors. The bottom container holds a battery for powering the compressors. The compressors are in the upper compartment, above the waterline, and thus are not water-cooled.